JP2509820B2 - Film forming equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film forming apparatus.

(Prior Art) Generally, a physical vapor deposition method (PVD) such as vapor deposition or sputtering has been used for many years as a technique for depositing a metal thin film on a semiconductor integrated circuit to perform wiring and the like.

However, due to the higher integration, higher speed, and higher density of integrated circuits such as VLSI, because of the formation of gate electrodes, contact holes, through holes, etc., the resistance is lower than that of polycrystalline Si by one digit or more. A technique for depositing a metal thin film of a refractory metal such as (tungsten) is important.

As a means for forming the metal thin film as described above, the metal thin film is formed by a metal CVD apparatus for growing a film growth gas on the surface to be processed of the substrate to be processed. Also, recently
In order to form a thin film more uniformly, the substrate to be processed is fixed to a quartz plate, and the substrate to be processed is heated by irradiating heating light such as infrared light from the side of the quartz plate.
Some perform D processing.

(Problems to be Solved by the Invention) However, when a metal thin film is formed by the CVD apparatus as described above, when a substrate to be processed, for example, a semiconductor wafer, is transferred from the pre-process apparatus for performing the CVD process to the CVD apparatus, the semiconductor For example, a natural oxide film is formed on the surface of the wafer, for example, on the order of several tens of liters, and even if a metal thin film is formed on this oxide film, the electrical contact resistance between silicon and metal increases, leading to deterioration in quality. There was a problem.

Further, for example, it is conceivable to form a metal thin film after etching the natural oxide film formed on the semiconductor wafer by converting the processing gas into plasma, but in order to make the film thickness uniform, infrared light is applied. When irradiating, the semiconductor wafer is fixed to transparent and insulating quartz etc., so even if a reaction gas is supplied, it does not turn into plasma or the plasma generation area is limited, and the natural oxide film cannot be uniformly etched. There was a problem.

The present invention has been made in view of the above points, and by completely removing the natural oxide film before forming a metal thin film, an increase in electrical contact resistance is prevented and a stable film is uniformly formed. An object is to provide a film forming apparatus capable of forming a film.

(Means for Solving the Problem) In order to achieve the above object, first, according to claim 1, the substrate is provided in a conductive processing container and holds the substrate to be processed in contact with a non-processing surface of the substrate. And a light heating means for heating the substrate to be processed with light,
In the film forming apparatus including a supply unit that supplies a film growth gas for forming a film on the processing surface of the substrate to be processed, and an exhaust unit that depressurizes the inside of the processing container to a predetermined pressure, the installation plate is quartz glass. At least one surface of the installation plate is coated with a conductive film having electrical conductivity and translucency, and the light heating unit is arranged at a position for irradiating the non-processed surface side of the substrate to be processed, A high-frequency power supply for generating plasma in the container, and an etching gas supply means for supplying an etching gas to the processing surface of the non-processing substrate are provided, and the power from the high-frequency power supply is applied to the conductive film. Provided is a film forming apparatus characterized by the above.

A film forming apparatus according to a second aspect of the present invention is the film forming apparatus according to the first aspect, wherein the film growth gas and the etching gas are further processed through the gas introduction port in the processing container. It is characterized in that a gas flow control plate configured to be supplied to the processing surface of the substrate is provided between the gas introduction port and the installation plate so as to be capable of approaching and separating from the installation plate.

The “light” when heating with light as used in claims 1 and 2 is a concept including infrared rays.

(Operation) In the film forming apparatus according to claim 1, the installation plate holding the substrate to be processed has a light-transmitting property, and the light heating means is arranged at a position to irradiate the non-processed surface side of the substrate to be processed. Because
The substrate to be processed can be heated by the light of the light heating means from the non-processed surface side of the substrate to be processed through the installation plate, and the substrate to be processed can be rapidly heated.

Moreover, since the installation plate is made of quartz glass, and at least one surface of the installation plate is coated with a conductive film having electrical conductivity and translucency, it also functions as an electrode, and high frequency power from a high frequency power source is applied. Thus, it is possible to turn the etching gas into plasma in the installation plate, that is, in the vicinity space corresponding to the substrate to be processed, and perform the etching process on the substrate to be processed. Therefore, for example, when forming a film on a substrate to be processed, it is possible to first remove the natural oxide film of the substrate to be processed by etching and then perform the film forming process in the same processing container as it is.

Moreover, the installation plate is made of quartz glass, but since this quartz glass generally has a lower thermal conductivity than conductive metal, the escape of heat due to conduction is suppressed and the substrate to be processed can be efficiently heated. it can.

In the film forming apparatus of claim 2, the film growth gas and the etching gas are further supplied to the processing surface of the substrate to be processed through a gas introduction port in the processing container. Between the inlet and the installation plate, a gas flow control plate that can approach and separate from the installation plate is provided.
By appropriately adjusting the position of the gas flow control plate, the flow of gas can be controlled so that the gas contacts the processing surface of the substrate to be processed more uniformly. Therefore, for example, by changing the position of the gas flow control plate in the case of the etching process and the case of the film forming process, the gas flow can be made suitable for each.

(Example) Hereinafter, an example in which the present invention is applied to a thin film forming apparatus of a high melting point metal by single-wafer processing in a thin film forming step by chemical vapor deposition in a semiconductor manufacturing process will be described with reference to the drawings.

As shown in FIG. 1, above a dense cylindrical reaction chamber (1) made of Al (aluminum) whose wall surface can be cooled with cooling water or the like, a substrate to be processed, for example, a pattern structure of Si and SiO ₂ which is a surface to be processed. An installation plate (3) made of a material such as quartz glass, which can be installed so that the surface to be processed faces downward and which can be rapidly heated by heating light (rapid thermal), is provided. . This installation plate (3)
As shown in FIG. 2, a transparent conductive film (4) such as SnO ₂ or ITO having a thickness of, for example, several thousand Å is coated on the surface opposite to the surface on which the semiconductor wafer (2) is installed so as not to block the heating light. ing. In addition, above the installation plate (3), a cylindrical support (5) made of conductive material such as Al for contacting and supporting the periphery of the installation plate (3) is in contact with the translucent conductive film (4). The support (5) is connected to an RF power source (not shown).

In the vicinity of the installation plate (3), an elevating mechanism (6) such as an air cylinder is provided so that the semiconductor wafer (2) is fixed to the installation plate (3) by using, for example, the outer edge of the semiconductor wafer (2). A support (7) is provided. Further, an IR ray lamp (infrared ray lamp) (9) capable of heating the installation plate (3) to, for example, 300 ° C. to 1000 ° C. through a quartz glass window (8) is provided above the installation plate (3). There is. The reaction chamber (1) near the installation plate (3)
The upper wall is provided with, for example, two exhaust ports (10), and the exhaust ports (10) are capable of reducing the pressure inside the reaction chamber (1) to a desired pressure and discharging reaction gas, for example, turbo molecules. A vacuum pump (11) such as a pump is connected.

In addition, two independent ring-shaped gas inlets (12) having a number of minute outlets for outflowing a gas for film growth, a carrier gas, an etching gas, etc. are provided below the reaction chamber (1). Has been. These gas inlets (12) are connected to a gas supply source via a flow rate control function (13) such as a mass flow controller. Further, between the installation plate (3) and the gas introduction port (12), a disc-shaped control plate (15) having a moving mechanism (14) for linearly moving a stepping motor or the like for controlling the flow of gas. Is provided.

The semiconductor wafer (2) is loaded into and unloaded from the reaction chamber (1) on one side of the reaction chamber (1) via, for example, a gate valve (16) that can be opened and closed by raising and lowering, so that the semiconductor wafer (2) can be extended and contracted. A hand arm (17) that holds and conveys the wafer (2) and a mounting table (19) that can be raised and lowered by mounting a cassette (18) in which the wafers (2) are stacked and housed at a predetermined interval, for example, about 25 sheets. An airtight preparatory transfer chamber (20) is installed therein.

The operation of the film forming apparatus having the above configuration is controlled by the control section (21).

Next, a semiconductor wafer (2) using the above-described film forming apparatus
A method of forming a film on the substrate will be described with reference to the flowchart shown in FIG.

For example, the semiconductor wafer (2) to be processed is moved to 25
A cassette (18) containing about one sheet is installed on an installation stand (19) that can be moved up and down (A). At this time, the gate valve (1
With 6) closed, the inside of the reaction chamber (1) has already been depressurized by the movement of the vacuum pump (11) to a desired low pressure state. And after setting the cassette (18),
An open / close port (not shown) of the transfer preliminary chamber (20) is closed so as to be airtight, and a reaction chamber (1) is opened by a vacuum pump (not shown).
Reduce the pressure to the same level as (B).

Next, the gate valve (16) is opened (C), the desired low pressure state is maintained, and the height of the mounting table (19) is adjusted so that the semiconductor wafer (2) can be expanded and contracted by the hand arm (1).
At 7), one desired sheet is taken out from the cassette (18) and loaded into the reaction chamber (1) (D). At this time, the support (7) is lowered by the elevating mechanism (6), and the semiconductor wafer (2) is placed on the support (7) with the surface to be processed facing downward. Then, the support (7) is raised by the elevating mechanism (6), and the semiconductor wafer (2) is sandwiched between the installation plate (3) and the support (7) and installed (E).

When the installation of the semiconductor wafer (2) on the installation plate (3) is completed, the hand arm (17) is housed in the preliminary transfer chamber (20) and the gate valve (16) is closed (F).

Next, the processing on the surface to be processed of the semiconductor wafer (2) is started.

First, a cleaning process for etching and removing the natural oxide film formed on the semiconductor wafer (2) is performed.

In this process, the gas introduction port (12) is opened and the flow rate control mechanism (is controlled) while exhaust control is performed by the vacuum pump (11) so as to keep the reaction chamber (1) at a desired low pressure state, for example, several tens to several hundreds mmTorr. A process gas such as Ar or NF ₃ is uniformly diffused while the flow rate is adjusted in 13) and is supplied onto the semiconductor wafer (2).

Then, for an electric conductor support (5) connected to the installation plate (3), an RF power source (not shown)
The power of [W] is applied. Then, electric power is applied to the translucent conductive film (4) formed on the surface of the installation plate (3) made of quartz glass, which is connected to the support (5) of the conductor, and the reaction chamber (1) Is conductive, a discharge is generated between the translucent conductive film (4) and the processing gas supplied onto the semiconductor wafer (2) is turned into plasma, and the semiconductor wafer ( The natural oxide film formed in 2) is etched at, for example, about 10Å / min.
At this time, since the support (5) is heated to a high temperature by the application of the electric power, the support (5) is cooled and controlled to about 20 ° C. by a cooling mechanism (not shown).

After the etching process as described above is completed, a metal thin film is formed on the surface of the semiconductor wafer (2) to be processed by chemical vapor deposition (H).

In this treatment, the infrared light, which is the heating light from the IR lamp (7), is made of quartz glass while controlling the evacuation by the vacuum pump (11) so as to keep the reaction chamber (1) at a desired low pressure state, for example, 100 to 200 mmTorr. Irradiate the installation body (3). in this case,
Since the quartz glass and the translucent conductive film (4) coated on the quartz glass are transparent, the semiconductor wafer (2) installed in this installation body (3) is rapidly heated.

At this time, the temperature of the processed screen of the semiconductor wafer (2) is set to IR.
Infrared rays emitted from the semiconductor wafer (2) are controlled by a pyrometer so that the temperature of the lamp (9) is, for example, about 40 to 530 ° C, or the temperature of the semiconductor wafer (2) is directly detected by using a high-sensitivity thermocouple. And control.

Then, the gas inlet (12) is opened, and a film growth gas such as WF ₆ which constitutes a reaction gas in the flow rate control mechanism (13),
A carrier gas such as H ₂ and Ar is flowed out, and chemical vapor deposition is performed. When the semiconductor wafer (2) contacting surface of the support (5) is made of ceramic or the like having a low thermal conductivity during this treatment, the heat distribution of the semiconductor wafer (2) becomes uniform and uneven treatment can be prevented.

When the chemical vapor deposition is performed as described above, a film of metal such as W (tungsten) can be selectively deposited in holes and the like formed in the surface to be processed of the semiconductor wafer (2).

Then, when the desired film format is completed, the reaction gas is stopped from flowing out, and the supporting body (5) is lowered by the elevating mechanism (4) while supporting the semiconductor wafer (2), and the gate valve (16) is opened. (I), the semiconductor wafer (2) is unloaded from the reaction chamber (1) by the extendable and retractable hand arm (17) (J), and the gate valve (16) is closed (K) to complete the process.

After this process is completed, it is confirmed whether or not there is an unprocessed wafer in the cassette (18) (L), and when there is an unprocessed wafer, the above etching process and chemical vapor deposition process are executed again to remove the unprocessed wafer. If not, end.

As described above, when the substrate to be processed, for example, the mounting plate on which the semiconductor wafer is mounted, is made of quartz glass and the transparent conductive film is formed, the transparent conductive film is used during the etching process for cleaning. It becomes possible to perform stable plasma etching of the processing gas by applying electric power to the substrate, and it is possible to perform stable etching processing. Also, during film formation, the CVD processing is performed while irradiating infrared light, which is heating light, from the installation plate side. Therefore, uniform and stable film formation is possible.

Note that the present invention is not limited to the above-described embodiment, and for example, the surface on which the transparent conductive film is formed on the quartz glass installation plate on which the semiconductor wafer is installed in the reaction chamber is the surface on which the semiconductor wafer is installed. It may be formed, or may be formed on both sides, and in either case, the same effect as that of the above-described embodiment can be obtained.

Further, what is subjected to the etching treatment is not limited to the natural oxide film, and plasma etching may be performed as a pre-process of the CVD process performed later. Furthermore, the position of the disk-shaped control plate (15) provided between the installation plate (3) and the gas introduction port (12) is adjusted by the moving mechanism (14), so that the installed semiconductor wafer (2) The flow of the reaction gas can be controlled so that the reaction gas comes into contact with the surface to be treated more uniformly.

Further, in the above embodiment, the chemical vapor deposition method, so-called CV
Although the film formation process was performed by the D process, for example, plasma CVD
The process may do this.

Furthermore, when a thin film such as a W (tungsten) film is formed on the surface to be processed of a substrate to be processed such as a semiconductor wafer (2) by a chemical vapor deposition method, a wall of a reaction chamber (1) forming a closed container. Although very slight, a W film may adhere to the surface and be deposited. This reaction chamber (1)
The self-cleaning process of the W film adhered and deposited on the surface of the wall by plasma etching will be described.

A vacuum pump (11) is used to keep the inside of the reaction chamber (1) at a desired low pressure state, for example, several tens to several hundreds of mmTorr, in a state where a substrate to be processed, for example, a semiconductor wafer (2) is not placed on the installation plate (3). Exhaust control is performed. In this exhausted state, the gas inlet (12) is opened, and the processing gas such as NF ₃ is supplied into the reaction chamber (1) while controlling the flow rate by the flow rate controller (13). Then, an electric power from an RF power source (not shown), for example, 400, is applied to the support body (5) of the conductor connected to the installation plate (3).
Apply [W].

As a result, electric power is applied to the translucent conductive film (4) formed on the surface of the quartz glass installation plate (3) connected to the conductor support (5), and the reaction chamber (1 ) Is conductive, a discharge is generated between the transparent conductive film (4) and the processing gas NF ₃ supplied into the reaction chamber (1) is converted into plasma, which is converted into plasma. The W film deposited and deposited on the wall surface of the reaction chamber (1) is plasma-etched by the gas. The self-cleaning process of the reaction chamber by plasma etching as described above is performed every time a W film is deposited to some extent on the reaction chamber.

For example, it may be set in advance so that it is performed every time a predetermined number of substrates to be processed are subjected to CVD processing. Further, it goes without saying that the timing of self-cleaning may be selectively determined as appropriate because the amount deposited on the wall surface of the reaction chamber varies depending on the type of gas used in the CVD process.

By performing the self-cleaning every predetermined time as described above, the inside of the reaction chamber can be always kept clean, and the W film or the like deposited and deposited in the reaction chamber becomes dust and adversely affects the CVD process. Can be prevented.

(Effects of the Invention) According to the film forming apparatus described in claims 1 and 2, after the natural oxide film on the substrate to be processed is removed by etching, the film forming process can be performed in the same processing container as it is. Therefore, it is possible to remove an unnecessary film prior to the film forming process of the substrate to be processed, for example, a natural oxide film formed when being transported in the atmosphere. Moreover, since the film forming process can be subsequently performed in the same processing container,
It is possible to directly form a target film on the processed surface of the substrate to be processed without sandwiching a natural oxide film. Therefore, for example, when a metal thin film is formed, it is possible to prevent an increase in electrical contact resistance and form a stable film.

Further, the installation plate holding the substrate to be processed is made of quartz glass, one surface of which is coated with a conductive film having conductivity and translucency, and the light heating means irradiates the non-processed surface side of the substrate to be processed. Since the etching gas is turned into plasma in the vicinity space corresponding to the non-processed substrate, the non-processed substrate side is rapidly exposed to light from the non-processed surface side of the processed substrate through the installation plate because it is arranged at the position. It is also possible to heat to. Moreover, in the heating, the substrate to be processed can be efficiently heated.

Further, particularly in the film forming apparatus of claim 2, by adjusting the position of the gas flow control plate, the gas is more uniformly contacted with the processing surface of the substrate to be processed according to the processing,
The gas flow can be controlled. Therefore, processing uniformity is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a film forming apparatus for explaining an embodiment of the present invention, FIG. 2 is an enlarged view of an installation plate for installing a substrate to be processed in the film forming apparatus shown in FIG. 1, and FIG. The figure is a flow chart for explaining film formation by the film forming apparatus shown in FIG. 1 ... Reaction chamber, 2 ... Semiconductor wafer, 3 ... Installation plate, 4 ... Translucent conductive film, 5 ... Support, 9 ... IR lamp, 12 ... Gas inlet

Claims (2)

(57) [Claims] 1. An installation plate, which is provided in a conductive processing container and holds the substrate to be processed in contact with a non-processed surface of the substrate to be processed, and a light for heating the substrate to be processed by light. A film forming apparatus comprising: a heating unit; a supply unit that supplies a film growth gas for forming a film on the processing surface of the substrate to be processed; and an exhaust unit that depressurizes the inside of the processing container to a predetermined pressure. The plate is made of quartz glass, and at least one side surface of the installation plate is coated with a conductive film having conductivity and translucency, and the light heating means is arranged at a position for irradiating the non-processed surface side of the substrate to be processed. And a high-frequency power supply for generating plasma in the processing container, and an etching gas supply means for supplying an etching gas to the processing surface of the substrate to be processed, the power from the high-frequency power supply is applied to the conductive film. Characterized in that it is constructed as being film forming apparatus. 2. An installation plate, which is provided in a conductive processing container and holds the substrate to be processed in contact with a non-processed surface of the substrate to be processed, and a light for heating the substrate to be processed by light. A film forming apparatus comprising: a heating unit; a supply unit that supplies a film growth gas for forming a film on the processing surface of the substrate to be processed; and an exhaust unit that depressurizes the inside of the processing container to a predetermined pressure. The plate is made of quartz glass, and at least one side surface of the installation plate is coated with a conductive film having conductivity and translucency, and the light heating means is arranged at a position for irradiating the non-processed surface side of the substrate to be processed. And a high-frequency power supply for generating plasma in the processing container, and an etching gas supply means for supplying an etching gas to the processing surface of the substrate to be processed, the power from the high-frequency power supply is applied to the conductive film. The film growth gas and the etching gas are configured to be supplied to the processing surface of the substrate to be processed through a gas introduction port in a processing container. The film forming apparatus is characterized in that a gas flow control plate that can approach and separate from the installation plate is provided between them.